1. Field of the Invention
The present invention relates to an optical head apparatus which records or reproduces data with respect to an optical disk and an optical head transferring method. Furthermore, the present invention relates to an optical disk apparatus which uses the above-described optical head apparatus.
2. Description of the Related Art
As is well known, there has been widely prevailed so-called multi disk drive equipment which not only can record and reproduce data with respect to a CD (i.e., a compact disk) but also can record and reproduce data with respect to an optical disk such as a DVD (i.e., a digital versatile disk).
The multi disk drive equipment of this type is used in equipment incorporated in a note book type personal computer or the like in addition to use as external equipment for a desk top type personal computer or the like, and therefore, its outside dimension is reduced in size and thickness as possible.
There is provided a feed mechanism in a general optical disk apparatus since an optical head for recording and reproducing data with respect to the optical disk must be moved in the radial direction of the optical disk. Such a feed mechanism is configured in such a manner as to convert the rotating force of a motor into a linear motion by means of a gear and a rack so as to transmit the force to the optical head.
Consequently, a play, that is, a backlash generated when the gear and the rack mesh with each other induces a drawback from the viewpoint of the accuracy of the transfer of the optical head. As a result, suppression of such a backlash without degrading miniaturization has been an important problem to enhance the accuracy of the transfer of the optical head.
Jpn. Pat. Appln. KOKAI Publication No. 2002-216442 discloses the configuration in which two racks are superimposed one on another to urge each other oppositely in a longitudinal direction by resilient force, so as to achieve favorable meshing with a pinion gear. Moreover, Jpn. Pat. Appln. KOKAI Publication No. 11-353824 discloses the configuration in which a pinion is pressed against a rack via a spring.
However, in the former configuration, the two racks need be superimposed one on another, thereby inducing a complicated configuration. In contrast, in the latter configuration, since the rotating pinion is pressed against the rack via the spring, a supporting mechanism for the pinion has a complicated and huge configuration, thereby arising a problem that a size cannot be reduced.
Additionally, Jpn. Pat. Appln. KOKAI Publication No. 7-93920 discloses the configuration in which a feed rack is moved in parallel to a rod, and further, the driving force of a gear is made constant by making a load applied on the gear uniform, thus eliminating a backlash.
In addition, Jpn. Pat. Appln. KOKAI Publication No. 7-122004 discloses the configuration in which an optical pickup can be moved with smaller acceleration so as to enhance track followability by alleviating an influence of slide friction.
Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 7-147018 discloses the configuration in which a rack and a gear are brought into smooth contact with each other by integrally forming a base provided with the rack of a plastic-based material, thus reading information with high accuracy.
However, the techniques disclosed in Jpn. Pat. Appln. KOKAI Publication Nos. 7-93920, 7-122004 and 7-147018 merely have had the complicated configuration and the large size, and therefore, they have not reached a practical and satisfactory level in current circumstances.